1. Field of the Invention
This invention relates to an organopolysiloxane emulsion composition.
2. Description of the Prior Art
To obtain oil-in-water (o/w) or water-in-oil (w/o) emulsions by chiefly using various organopolysiloxanes as typified by dimethylpolysiloxane, various surface active agents of nonionic, anionic, cationic or amphoteric type having a higher hydrocarbon group as a hydrophobic group are used as emulsifying agents like the case when usual organic liquids, wax, polyethylene, etc. are emulsified.
In selecting a surface active agent from these, it is well known that the component to be emulsified must have an affinity for the hydrophobic group moiety of the surface active agent. However, it is also known to be true that commonly available organopolysiloxanes have a poor affinity for the hydrophobic group moiety of these surface active agents.
Accordingly, it is readily conjectured that employment of a surface active agent which has an organopolysiloxane moiety as the hydrophobic group would be effective for emulsifying the organopolysiloxanes. For example, Japanese Unexamined Patent Publications (KOKAI) No. 212321/1986 and No. 212324/1986 disclose that a block copolymer comprised of a polyoxyalkylene group attached to a side chain or to both ends or to both the side chain and the ends of the organopolysiloxane molecular chain can be used as an emulsifying agent for emulsifying relatively low molecular organopolysiloxanes. These silicone surface active agents, however, can emulsify the relatively low molecular organopolysiloxanes, but may give insufficient performance to emulsify organopolysiloxanes having a higher polymerization degree, and thus have been unable to obtain either w/o emulsions or o/w emulsions having a good stability.
In KAGAKU KOGYO ZASSHI (Journal of Chemical Industry), Vol. 73, No. 6, and HYOMEN (Surface), Vol. 7, No. 11, Maki and Komori report an organopolysiloxane surface active agent which is an AB type block copolymer composed of a relatively low molecular dimethylpolysiloxane and a polyoxyalkylene. The performance of this organopolysiloxane to emulsify organopolysiloxanes.
In general, however, in silicone emulsifying agents obtained by conventional techniques, AB-block copolymers are mixtures consisting of a polymer containing functional groups at both ends, a polymer terminated with triorganosiloxy groups at both ends and a polymer having a functional group only at one end, except the case when a diorganopolysiloxane moiety of the copolymer is prepared from a starting low molecular substance feasible for distillation, separation and purification. Therefore, the AB-block copolymers can not exhibit any good surface activity.